Recently, liquid crystal displays for television receivers, personal computers and cell phones are trending toward fineness and miniaturization, with which the wirings in driver integrated circuits are provided at narrower pitches. To assure high productivity, wirings of a tape carrier package (TCP) with integrated circuits mounted thereon and of a liquid crystal display substrate are connected under such severe thermocompression bonding conditions as a temperature of 200° C., a pressure of 2 MPa and a time of 10 to 30 seconds.
In such connection of the wirings, anisotropic conductive films, such as one disclosed in JP-A-3(1991)/46707, that comprise conductive fine particles dispersed in a resin to allow for anisotropy, are of conventional use. The anisotropic conductive films, however, have cost problems: the production cost is high because the film production involves a separator film, making the anisotropic conductive films expensive, and a dedicated automatic peeling machine needs to be provided to apply the films. Also the anisotropic conductive films cannot exhibit sufficient bond strength and suffers a lowering in connection reliability under hot and humid conditions.
Materials for solving the problems include pastes for circuit connection, anisotropic conductive pastes and anisotropic conductive adhesives that are liquid at room temperature, as disclosed in JP-A-62 (1987)/40183, JP-A-62(1987)/76215 and JP-A-62(1987)/176139. However, these pastes for circuit connection, anisotropic conductive pastes and anisotropic conductive adhesives drastically decrease its viscosity on thermocompression bonding process with a sharp rise in temperature. As a result voids and bleeding contamination occur due to the liquid flow at the time of thermocompression bonding. Conductive particles, present in the pastes for circuit connection, anisotropic conductive pastes and anisotropic conductive adhesives, partly agglomerate to cause conductive failure in the direction of compression. Moreover, after the pastes for circuit connection, the anisotropic conductive pastes, etc. are cured, the connection reliability thereof cannot be held at high temperatures and high humidity because of the bubbles remaining in the cured products. Also, the cured products, although high in strength, have no repairability.
Thus, materials that can be free of bubbles and have high bonding reliability, connection reliability and repairability when cured under such severe thermocompression bonding conditions as a temperature of 200° C., a pressure of 2 MPa and a time of 10 to 30 seconds, are desired.